A toggle fastener may be defined as one which comprises two components to be fixed on the respective parts namely a mounting plate and a keeper which are to be releasably fastened together. The plate provides a pivotal mounting on a first axis for a hasp lever, and the latter provides a pivotal mounting on a second axis for a bail, claw or other component (herein called `bail`) which is apt to engage with the keeper. The first axis lies between the keeper and the second axis when the fastener is engaged. In the engaged position, a line of engagement between the keeper and bail may be generally co-planar with the first and second axes, but usually the design is such that the second axis crosses a plane containing the said line of engagement and the first axis during the final stage of a fastener closing movement and this `overcenter` movement provides a security of fastening, that is holds the fastener in the closed position against inadvertent release. Additional security means may be provided for example in the form of a catch which has to be moved against a spring before the hasp can be returned overcenter to release the bail, or in the form of a lug which extends through a movable part and is apertured to take a padlock or seal. A toggle fastener as defined in the foregoing words (with or without the additional security means) is conveniently called "of the kind referred to" and represents the starting point of the present invention.
The problem with fasteners of the kind referred to is that in the engaged position one or other end of the bail may act as a hinge and allow relative movement of the parts which are secured. Thus for example a panel fixed by toggle fasteners on opposite edges may vibrate with the respective bails acting as swinging links. Simple toggle fasteners are not recommended for this kind of use for this reason, although they are often so used and are maligned when they do not perform as expected.
The object of the invention is to solve this problem.